Vertical axis windmill

ABSTRACT

A vertical shaft windmill is provided in which: a casing ( 7 ) extends further upward than a lowest arm ( 5 L); a radial bearing (BI) is fixed to the outer part of the casing ( 7 ); and the arm ( 5 L) is mounted for rotation to the casing ( 7 ) through the radial bearing (BI). Unstable conditions in the overhang region can be eliminated without decreasing its wind receiving area and without interference with other members.

TECHNICAL FIELD

This invention relates to a vertical shaft windmill with its rotaryshaft directed generally perpendicular to an air flow (wind), such as aDarius type windmill.

BACKGROUND ART

The rotary shaft of a vertical shaft windmill extends in the verticaldirection. In the vertical shaft windmill, the rotary shaft is supportedby a thrust bearing at its lowermost portion, and by a radial bearingthereabove.

Here, in order for the rotary shaft as a rotary body to be supported bya radial bearing, the radial bearing should be fixed to a casing as afixed member.

Hitherto, the radial bearing was provided in a region covered with thecasing. The radial bearing provided inside the casing supports therotary shaft with its inner race, having its outer race fixed to thecasing. The casing covers the region below arms connecting the blade andthe rotary shaft, so that interference with the arms is avoided.

Here, in a region not covered with the casing (the region above thecasing), or a so-called “overhang region,” the rotary shaft is notsupported by the radial bearing.

However, in the overhang region where the rotary shaft is not supportedby the radial bearing, the vertically extending rotary shaft can beunstable. In such a case (where the rotary shaft becomes unstable), therotary shaft will “swing” or make a precession, which might causeinterference of the blade and arms with other members or equipment.

In addition, this results in a load concentration on the uppermostradial bearing and there is a danger of damaging the uppermost radialbearing.

On the other hand, if the overhang portion is shortened, the foregoingunstable condition is improved. However, the length of the blade also isshorter and its wind receiving area for the rotation is decreased aswell, hindering the fundamental function as a windmill.

In view of the foregoing problems in the prior art, an object of thisinvention is to provide a vertical shaft windmill capable of eliminatingunstable conditions in the overhang region without decreasing the windreceiving area and without interference with other members.

DISCLOSURE OF INVENTION

The object of this invention is to provide a vertical shaft windmill asshown for example in FIG. 1-FIG. 5, comprising: a blade 4 for receivinga wind to obtain rotational force; a plurality of arms 5L, 5M, 5Udisposed in vertical relation for supporting the blade 4; a rotary shaft6 disposed vertically for receiving the rotational force of the blade 4through the arms 5M, 5U; a casing 7 for housing the rotary shaft 6,extending further upward than the lowest arm 5L of the plurality of arms5L, 5M, 5U; and a radial bearing BI fixed to the outer part of thecasing 7 for rotatably mounting the lowest arm 5L to the casing 7.

In this arrangement, since there are provided a casing for housing therotary shaft, extending further upward than the lowest arm of theplurality of arms, and a radial bearing fixed to the outer part of thecasing for mounting the lowest arm to the casing for rotation, unstableconditions of the blade and the rotary shaft can be eliminated withoutdecreasing the wind receiving blade area.

The vertical shaft windmill 3 may, as shown for example in FIG. 5 andFIG. 6, comprise a cover member 9 disposed radially outwardly at anexterior of the radial bearing BI.

In this arrangement, since a cover member 9 disposed radially outwardlyat an exterior of the radial bearing BI is provided, possible rustgeneration in the radial bearing or ingress of foreign matters into thebearing can be prevented.

The vertical shaft windmill 3 may, as shown for example in FIG. 7, FIG.8 and FIG. 9, further comprise an arm connecting member 10 placedbetween the radial bearing BI and the arms 5M, 5U and formed with arecess 10 e having a taper of larger radial inside and smaller radialoutside; and radially inner end of the arm 5M, 5U may be formed in theshape complementary to the recess 10 e.

Further, in the vertical shaft windmill 3, as shown for example in FIG.10, the arm 5L, 5M, 5U may be formed hollow and comprise a reinforcementmember 55M made of a light material, with a specific gravity of nolarger than 3.0, different from that of the arm 5L, 5M, 5U and disposedat the radially inner end of the arm 5L, 5M, 5U, partly inserted in thearm 5L, 5M, 5U (or the arm body).

Further, the vertical shaft windmill 3 may as shown for example in FIG.12 and FIG. 13, comprise a lid-like member 20 covering the uppermost end7C of the casing 7; and a labyrinthine structure may be constituted at aportion covered with the lid-like member.

Further, the above vertical shaft windmill may as shown for example inFIG. 16 and FIG. 19, comprise a generator GM driven by the rotationalforce of the rotary shaft 6; and the rotary shaft 6 may be constitutedintegrally with a rotary shaft of the generator GM.

Further, as shown for example in FIG. 18, the vertical shaft windmillmay comprise a solar battery panel 110 mounted on the outsidecircumference of the casing 7.

Further, as shown for example in FIG. 16 and FIG. 19, the generator GMmay be adapted to operate also as a motor, and may be adapted to: supplyelectric power to a commercial power source when operating as agenerator; and be supplied from the commercial power source whenoperating as a motor.

Further, as shown for example in FIG. 19, the generator may be adaptedto: be supplied with electric power from a battery when operating as amotor; and store electric power in the battery so as to supply electricpower from the battery to a commercial power source or as in-houseelectric power, as required, when operating as a generator.

The basic Japanese Patent Application No. 2002-055328 filed on Mar. 1,2002 is hereby incorporated in its entirety by reference into thepresent application.

The present invention will become more fully understood from thedetailed description given hereinbelow. However, the detaileddescription and the specific embodiment are illustrated of desiredembodiments of the present invention and are described only for thepurpose of explanation. Various changes and modifications will beapparent to those ordinary skilled in the art on the basis of thedetailed description.

The applicant has no intention to give to public any disclosedembodiment. Among the disclosed changes and modifications, those whichmay not literally fall within the scope of the patent claims constitute,therefore, a part of the present invention in the sense of doctrine ofequivalents.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a front sectional view of a Darius type windmill to which thisinvention is applied.

FIG. 2 is an enlarged view of a portion designated by the symbol F2 ofFIG. 1.

FIG. 3 is a plan view of a lower arm connection and bearing supportmember of the embodiment of this invention.

FIG. 4 is a sectional view taken along the line A-A of FIG. 3.

FIG. 5 is a sectional view of a cover member of the embodiment of thisinvention.

FIG. 6 is a plan view corresponding to FIG. 5.

FIG. 7 is an enlarged view of a portion designated by the symbol F7 ofFIG. 1.

FIG. 8 is a plan view of an upper coupling of the embodiment of thisinvention.

FIG. 9 is a sectional view taken along the line C-C of FIG. 8.

FIG. 10 is a plan view of the radially inner end of a lower arm of theembodiment of this invention.

FIG. 11 is an enlarged view of a portion designated by the symbol F11 ofFIG. 1.

FIG. 12 is a vertical sectional view of a lid-like member of theembodiment of this invention.

FIG. 13 is a plan view corresponding to FIG. 12.

FIG. 14 is a vertical sectional view of the uppermost end of a casing ofthe embodiment of this invention.

FIG. 15 is a plan view corresponding to FIG. 14.

FIG. 16 is a structural block diagram of a control device for thechangeover between a generator function and a motor function of agenerator-motor of the embodiment of this invention.

FIG. 17 is a control flowchart showing a control method for thechangeover between the generator function and the motor function of thegenerator-motor of the embodiment of this invention.

FIG. 18 is a sectional view taken along the line B-B of FIG. 1.

FIG. 19 is a structural block diagram of a control device for thechangeover between a generator function and a motor function of agenerator-motor of another embodiment of this invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Now, an embodiment of this invention will be described with reference tothe accompanying drawings.

In FIG. 1, a Darius type windmill 3 of the vertical shaft windmill isdisposed on a base 2 fixed firmly to the ground foundation by an anchor1.

In the Darius type windmill 3, a blade 4 receiving a wind for therotational force is supported on a rotary shaft 6 and a casing 7 with aplurality of arms (in the illustration, they are provided in three tiersof upper, middle and lower ones: an upper arm is designated by symbol5U, a middle arm by symbol 5M, and a lower arm by symbol 5L).

Here, in a conventional vertical shaft windmill, the rotary shaft issupported inside the casing radially by radial bearings and axially by alowermost thrust bearing.

In addition, in a conventional bearing, to avoid interference of thecasing with the arms, the casing is arranged such that it surrounds aregion below the lowest arm (the lower arm 5L, for example, in FIG. 1);and the casing is by no means located above the lowest arm (the lowerarm).

On the contrary, in the embodiment shown in the figure, with the help ofan inner-race-fixed radial bearing BI and the surrounding structure, thecasing 7 extends to a region above the lowest arm, or the lower arm 5L,and the overhang (portion not covered by the casing 7) is smalleraccordingly.

That is, since with the help of the inner-race-fixed radial bearing BIand the surrounding structure described below, the lower arm 5L issupported for rotation to the casing 7, interference of the lower arm 5Lwith the casing 7 is prevented.

In addition, as a result of the interference of the lower arm 5L withthe casing 7 being prevented, the casing 7 is allowed to extend to theregion above the lower arm 5L near the middle arm 5M, so that theuppermost radial bearing BR can also be provided at a position near themiddle arm 5M.

As a result, the “overhang,” or the region where the rotary shaftextends further upward than the uppermost radial bearing BR can beshortened by the distance to the radial bearing BI of the lower arm 5L,improving stability of the whole vertical shaft windmill 3.

In FIG. 1, symbol BS designates a thrust bearing disposed at the lowerend of the rotary shaft 6 for supporting a downward load for smoothrotation.

Now, the inner-race-fixed radial bearing BI and the surroundingstructure will be described with reference to FIG. 2-FIG. 6, inaddition.

As is clear from FIG. 1 and FIG. 2 (partial enlarged view of theinner-race-fixed radial bearing BI and its surroundings), and especiallyfrom FIG. 2, in the region where the lower arm 5L extends in the radialdirection, the casing 7 has the shape of being recessed radiallyinwardly, and in the recessed portion 7A of the casing 7 is provided aninner-race-fixed radial bearing mounting member 7B formed in a ring-likeand recessed shape as a whole.

The inner-race-fixed radial bearing BI is provided on the outer side ofthe inner-race-fixed radial bearing mounting member 7B. Here, theinner-race-fixed radial bearing mounting member 7B constitutes a part ofthe casing 7; the inner-race-fixed radial bearing BI is disposedexternally on the casing; and the inner race of the inner-race-fixedradial bearing BI is fixed to the inner-race-fixed radial bearingmounting member 7B constituting a part of the casing 7.

Further, the inner-race-fixed radial bearing mounting member 7B will bedescribed in detail, as well as a mounting procedure of theinner-race-fixed radial bearing BI.

The casing 7 is comprised of a lower casing 70 located below the lowerarm 5L and an upper casing 75 located above the lower arm 5L.

A lower connection flange 70F is fixed to the upper end of the lowercasing 70, and an upper connection flange 75F to the lower end of theupper casing 75.

The inner-race-fixed radial bearing mounting member 7B is constituted bya lower flange 70B and an upper flange 75B.

The lower flange 70B is comprised of a flange portion 70Ba, and acylindrical boss 70Bb formed with a through hole 70Bh for the rotaryshaft 6 to pass. The boss 70Bb is formed with a stepped portion 70Bdhaving a small diameter portion 70Bs and a large diameter portion at theoutside circumference. The small diameter portion 70Bs is inserted inthe inner race of the inner-race-fixed radial bearing BI in anintermediate fitting relation, for example.

On the other hand, the upper flange 75B is formed, centrally, with athrough hole 75Bh for the rotary shaft 6 to pass, and provided,centrally on the lower side, with a stepped hole 75Ba into which an end(small diameter portion 70Bs) of the boss 70Bb of the lower flange 70Bis fitted.

In the end face of the boss 70Bb of the lower flange 70B and around thethrough hole 75 Bh of the upper flange 75B are provided attachment holesfor attaching the flanges each other with bolts B1, so that they areassembled together as an inner-race-fixed radial bearing mounting member7B.

In order to fix the inner-race-fixed radial bearing BI (assembled) tothe inner-race-fixed radial bearing mounting member 7B, first insert,into the inner race of the inner-race-fixed radial bearing BI assembledto the lower arm 5L using the method described later, the small diameterportion 70Bs of the boss 70Bb of the lower flange 70B temporarilysecured to the lower connection flange 70F of the lower casing 70, withthe rotary shaft 6 inserted in the through hole 70 Bh.

Then, fit the small diameter portion 70Bs of the boss 70Bb of the lowerflange 70B into the inner portion of the upper flange 75B. After thefitting, bring the end face of the small diameter portion 70Bs intoabutment against the bottom of the stepped hole 75 Ba portion of theupper flange 75B.

When the bolts B1 are fastened, with both parts in abutment against eachother, the lower flange 70B and the upper flange 75B are joined togetherto be assembled as the inner-race-fixed radial bearing mounting member7B.

With reference to FIG. 3 and FIG. 4, a lower arm connection and bearingsupport member (hereinafter abbreviated as connection and supportmember) 8 will be described.

The connection and support member 8 includes a cylindrical bearingsupport boss 80 having a stepped hole 82 formed of a small hole 82 a anda large hole 82 b, and a lower arm connection flange 85 extendingradially outwardly from the outside circumference of the bearing supportboss 80.

The stepped hole 82 receives the inner-race-fixed radial bearing BI tobe fitted therein to support the bearing.

The lower arm connection flange 85 extends radially from the outsidecircumference of the bearing support boss 80, having a plurality (threein the figure) of recesses 87, each having a taper of larger radialinside and smaller radial outside, formed radially from the center ofthe boss 80 at regular (equal) angular intervals on the same side asthat on which the large hole 82 b of the bearing support boss 80 opens.

The radially innermost end of the lower arm 5L (described later) in theshape complementary to the recess 87 is fitted in the recess 87, and thelower arm connection flange 85 and an arm locking member 89 (see FIG. 2)are connected with fastening bolts B2 (see FIG. 2) such that theinnermost end of the lower arm 5L is held therebetween.

A ring-like grease groove designated by reference numeral 82 c in FIG.4, when filled with grease, serves as means for maintaining lubricationof the inner-race-fixed radial bearing fitted in the stepped hole 82.

The construction shown in FIG. 2-FIG. 4 allows the lower arm 5L designedfor rotation to be supported for rotation on the casing 7 (7B) notdesigned for rotation, by the inner-race-fixed radial bearing BI.

Referring to FIG. 2 again, the outline of a cover member (cover forpreventing ingress of foreign matters) 9 extending vertically near theinner-race-fixed radial bearing BI thereabove and therebelow, will bedescribed.

The cover member 9 is preferably made of material of a high weatherresistance and a low aging deterioration, and in the embodimentillustrated, it is made of a metal. However, plastics, hard rubbers andthe like may be used.

Attention should be paid to the following points in installing the covermember 9.

The region from the lower arm 5L to the outer race of theinner-race-fixed radial bearing BI (lower arm 5L and connection andsupport member 8) rotates about the axis of the rotary shaft 6. There ispreferably no contact resistance between the cover member 9, and thelower arm 5L and connection and support member 8. Therefore, in theillustrated embodiment, a small clearance is provided between the tip ofthe cover, and the lower arm 5L and connection and support member 8(non-contact).

However, if the contact resistance is relatively small, the cover member9 (for example, constituted of a diaphragm) may be in contact with thelower arm 5L and connection and support member 8.

The cover member 9 will be described in detail with reference to FIG. 5and FIG. 6. The two, upper and lower cover members 9 shown in FIG. 2 areof the same shape.

The cover member 9, as shown in FIG. 5, is comprised of a ring-likeflange portion 9 a having a plurality of mounting holes 9 c, and acylindrical portion 9 b, made of a thin plate, provided on one side ofthe flange portion 9 a.

The inner-race-fixed radial bearing BI would be exposed to the externalenvironment because it is not covered with the casing 7 (7B): howeversince the cover member 9 is provided, a danger of abrasion due toingress of foreign matters is completely prevented.

In FIG. 1, the construction described with reference to FIG. 2-FIG. 6allows the casing 7 to extend to a region near the middle arm M.

In a region above the middle arm 5M, the arms (middle arm 5M and upperarm 5U in FIG. 1) are connected to the rotary shaft 6 by couplings(described below).

In FIG. 7, a coupling 14 is comprised of an upper coupling 10 and alower coupling 12, and the upper coupling 10 and lower coupling 12 holdthe radially inner end of the middle arm 5M therebetween.

The upper coupling 10 and the lower coupling 12 are of a similar shape,and only the upper coupling 10 will be described more specifically withreference to FIG. 8 and FIG. 9.

As shown in FIG. 8 and FIG. 9, the upper coupling 10 is comprised of adisk-like flange 10 a, and a boss 10 b provided on one side of thedisk-like flange 10 a, and the upper coupling 10 is formed, centrally,with an engagement hole 10 d having a key slot 10 c for engaging therotary shaft 6.

On the side of the disk-like flange 10 a opposite to the side on whichthe boss 10 b is provided are formed a plurality of tapered grooves orrecesses 10 e. The tape is of a width getting larger from the outsidecircumference toward the center (radially inwardly) of the disk-likeflange 10 a.

Although the three recesses provided in the embodiment of FIG. 8 arejoined together at the center, they may be formed separately. In aregion of the recesses 10 e are provided a plurality (six for eachmounting portion) of mounting holes 10 f along two pitch circles.

The middle arm 5M connected to the upper coupling 10 has its end formedin the shape of a taper such that the width of the mounting end isincreased radially inwardly as in the recess 10 e.

Therefore, when the tapered end of the middle arm 5M is fitted in therecesses 10 e of the upper coupling 10 and the lower coupling 12 (havingtapered recesses of the same shape as the recesses 10 e of the uppercoupling 10) and the middle arm 5M is held between the upper and lowercouplings and fastened with fastening bolts and nuts B3, the middle arm5M is connected by the upper and lower couplings 10, 12. The coupling 14(assembly of the upper and lower couplings 10, 12) and the rotary shaft6 are secured to each other by an unillustrated key and the key slot 10c.

Now, with reference to FIG. 10, the construction and shape of the middlearm 5M (the radially inner end among others) will be described. Themiddle arm 5M is comprised of an arm body 50M, and a reinforcementmember 55M located at its radially inner end and adjoining the arm body50M.

As shown in FIG. 10, in a region of the middle arm 5M near the radiallyinner end, the portion to be fitted in the recesses 10 e of the upperand lower couplings 10, 12 is constituted by the reinforcement member55M (made of aluminum). The reinforcement member 55M has a radiallyoutwardly extending portion inserted in the arm body 50M in the radiallyinnermost region of the arm body 50M.

A sufficient strength is required to connect the rotary shaft 6 and thethin-walled arm body 50M, and reinforcement with a metallic materialrich in tenacity is preferable. On the other hand, weight reduction isrequired for improvement in the windmill efficiency, so that, aluminumwith a small specific gravity is adopted as a material of thereinforcement member 55M in the illustrated embodiment.

Hitherto, there have been arms formed only from FRP, but they haveproblems in terms of price and delivery time, and if they are formedonly from aluminum, another problem is raised of increased total weight.

However, if the construction described with reference to FIG. 10 isadopted, a structure is materialized free from problems in terms notonly of price and delivery time but also strength and weight.

Connection between the aluminum reinforcement member 55M and the FRP armbody 50M of thin-walled hollow shape has sufficient strength only withadhesive applied to the connecting portions; however, in the illustratedembodiment, they are joined together with reamer bolts B4 forimprovement in safety (for the prevention of separation of aluminum andFRP).

Here, mounting holes are provided in the connecting section of thereinforcement member 55M and arm body 50M such that the reamer bolts B4are disposed in a staggered relation. If the reamer bolts B4 aredisposed in a row, the FRP arm body 50M of thin-walled hollow shapemight be broken along the row of the reamer bolts B4 and the object ofthe staggered arrangement is to prevent this breakage.

In FIG. 10, the arrangement of the reamer bolts B4 is asymmetrical inthe lateral direction. This is because the arm thickness after fasteningis equalized in the lateral direction, based on the shape of the armsection (lens-like shape with its thickness in the lateral directionasymmetrical), for the prevention of breakage due to excessive reductionin thickness on one side.

In order to connect lower arm 5L in the radially outward region of theinner-race-fixed radial bearing BI as described in FIG. 2-FIG. 6,connection is performed approximately in the same manner as described inFIG. 7-FIG. 10.

While, the lower arm 5L is held between the lower arm connection andbearing support member 8 and arm locking member 89 in the verticaldirection in FIG. 2-FIG. 6, the corresponding arm is held between theupper and lower couplings 10, 12 in FIG. 7-FIG. 10.

In this point, both cases are the same. For example, as shown in FIG. 3,the lower arm connection and bearing support member 8 is formed withtapered recesses 87 and the radially innermost portion of the arm of theshape corresponding to the recesses 87 is fitted therein.

Such a construction is the same as that shown in FIG. 8.

Returning to FIG. 1 and referring to FIG. 11, at the upper end of therotary shaft 6 (connecting section of the upper arm 5U and rotary shaft6), unlike the structure shown in FIG. 7, the upper arm 5U is connectedby a lower coupling 16 and an upper flat plate-like member 18 (FIG. 11)and there is provided no upper coupling.

The connecting structure of the upper arm 5U at the radially outermostportion, that is, the connecting structure of the upper arm 5U and theblade 4 is different from that described with reference to FIG. 7-FIG.10.

This is because, in the illustrated embodiment, the material of therotary shaft 6 is different from that of the arms (5U, 5M, 5L), but thematerial of the arms (5U, 5M, 5L) and that of the blade 4 are the same(FRP).

Part of the shape of the blade 4 will be described. At the lower end 4 eof the blade 4 shown in FIG. 1 is provided an unillustrated drain holefor draining water.

As for the drain hole, a coreless cavity of the hollow blade 4 may beused as it is, or, after closing the lower end of the blade, a holesmaller than the section of the cavity may be formed.

Referring to FIG. 7 again, over the uppermost end 7C of the casing as anon-rotary member is placed a lid-like member 20, and the portioncovered with the lid-like member 20 constitutes a labyrinthine structureby the uppermost end 7C of the casing and lid-like member 20.

The lid-like member 20 is fixed to the rotary shaft 6, as a rotarymember.

The lid-like member 20 is shown in FIG. 12 and FIG. 13 and the uppermostend 7C of the casing is shown in FIG. 14 and FIG. 15.

The labyrinthine structure will be described with reference to FIG. 7and FIG. 12-FIG. 15.

First, the uppermost end 7C of the casing, a non-rotary member, will bedescribed with reference to FIG. 14 and FIG. 15.

The casing uppermost end 7C is comprised of: a disk-like flange portion7Cf having a plurality of mounting holes 7Ca near the outsidecircumference and a hole portion 7Cb at the center; and a conical roofportion 7Cd, extending on the upper surface of the flange portion 7Cffrom the upper end of the hole portion 7Cb obliquely upwardly toward thecenter and having a hole 7Cc for the rotary shaft to pass.

The rotary shaft through hole 7Cc of the conical roof portion 7Cd isprovided, vertically, with an inner cylindrical partition wall 21 withan inside diameter approximately equal to the rotary shaft through hole7Cc. In addition, to the conical roof portion 7Cd is fixed an outercylindrical partition wall 23 with a larger diameter than that of theinner cylindrical partition wall 21, disposed concentrically with theinner cylindrical partition wall 21.

Now, the lid-like member 20 as a rotary member will be described indetail with reference to FIG. 12 and FIG. 13.

The lid-like member 20 is comprised of a boss 20 b having at the centera fitting hole 20 a to be fitted on the rotary shaft, and a conical body20 c extending obliquely downwardly and outwardly from the lower end ofthe outside circumference of the boss 20 b.

In the boss 20 b is formed, radially, female screws 20 d for bolts forinterlocking the lid-like member 20 with the rotary shaft 6.

To the lower surface of the conical body 20 c are fixed an innercylindrical partition wall 22 and an outer cylindrical partition wall 24both disposed coaxially with the conical body 20 c and extendingvertically downwardly.

Here, the positional relation of the inner cylindrical partition wall 21and outer cylindrical partition wall 23 of the casing uppermost end 7C,and the inner cylindrical partition wall 22 and outer cylindricalpartition wall 24 of the lid-like member 20 is preferably such that theinner cylindrical partition wall 22 of the lid-like member 20 ispositioned approximately in the middle between the inner cylindricalpartition wall 21 and outer cylindrical partition wall 23 of the casinguppermost end 7C while the outer cylindrical partition wall 23 of thecasing uppermost end 7C is positioned approximately in the middlebetween the inner cylindrical partition wall 22 and outer cylindricalpartition wall 24 of the lid-like member 20, to constitute thelabyrinthine structure.

As described above, a labyrinthine structure is adopted in which thecasing uppermost end 7C is integrated with the partition walls (innercylindrical partition wall 21 and outer cylindrical partition wall 23)and the lid-like member 20 as a rotary body is also integrated with thepartition walls (inner cylindrical partition wall 22 and outercylindrical partition wall 24).

Such a labyrinthine structure allows heat generated within the casingduring power generation (or in the case of operation as a motor) andheat generated by the rolling friction of the bearings to be releasedeasily and enables prevention of ingress of rainwater.

Returning to FIG. 1, in the casing 7 is provided rotationalforce-to-power conversion means for converting rotation of the rotaryshaft 6 into electric power, or a generator GM. Here, the generator GMis adapted to operate as s motor when a current is supplied to the coil.

The illustrated embodiment is arranged such that, a current (commercialelectric power) is supplied to the coil of the generator GM so that thegenerator is operated as a motor when the wind velocity is not enough toovercome the static rolling resistance.

If the windmill 3 starts rotating, it rotates satisfactorily through thewind velocity as large as to overcome the rolling resistance. If itrotates as fast as to overcome the rolling resistance, the motor may bestopped and operated as a generator.

With reference to FIG. 16 and FIG. 17, a control device for thechangeover between generator and motor and its control will bedescribed.

The control device for the changeover between generator and motor shownin FIG. 16 has: generator-motor GM for generating electric power throughrotational force of the rotary shaft 6 of the vertical shaft windmill 3;a current changeover switch 60 connected to the generator-motor GM via apower line L1; a rectifier 80 connected to the current changeover switch60 via a power line L2; and a commercial power source (external power)100 connected to the current changeover switch 60 via a power line L3,and is arranged such that control means 90 receiving an input signalfrom an anemometer W via an input signal line Li sends an output signalto the current changeover switch 60 via an output signal line Lo inorder to change the function of the generator-motor GM to either agenerator function or a motor function based on the input signal.

Now, using FIG. 17 and with reference to FIG. 16, a control method forthe changeover between generator and motor will be described.

At step S1, the control means 90 reads a signal from the anemometer W,and the procedure proceeds to step S2.

At step S2, the control means 90 judges whether or not the current windvelocity overcomes the rolling resistance of the whole windmill 3. Ifthe wind velocity is large enough to overcome the rolling resistance(YES of step S2), the procedure proceeds to step S3 and if not, theprocedure returns to step S1.

At step S3, the control means 90 supplies commercial power from thecommercial power source 100 to the generator-motor GM for the changeoverswitch 60 to be changed from the generator function to the motorfunction.

At next step S4, the control means 90 judges whether or not the rotatingspeed of the generator-motor GM is equal to or higher than a givenvalue.

If the rotating speed is equal to or higher than a given value (YES ofstep S4), the procedure proceeds to next step S5 and if not (NO of stepS4), the procedure returns to step S3.

At step S5, the control means 90 sends a control signal to thechangeover switch so that the function of the generator-motor GM ischanged from the motor function to the generator function, and controlcomes to an end.

Such an arrangement allows the windmill 3 to rotate for the powergeneration even when the wind velocity is not so high as to overcome thestatic rolling resistance. Requirements to utilize the windmill may bemoderated to enhance the efficiency (availability) of the windmill 3.

In FIG. 18 (sectional view taken along the line B-B of FIG. 1), a solarbattery panel 110 is mounted on the outside circumferential surface ofthe casing 7 surrounding the unillustrated rotary shaft. Regarding thesolar battery panel 110, flexible panels are attached to the casing 7throughout the outside circumferential surface by means of two stays 120for each panel. Installation of the solar panel throughout the outsidecircumferential surface enables photovoltaic power generationirrespective of the position of the sun.

With reference to FIG. 19, another embodiment of this invention will bedescribed, which shows an example of a vertical shaft windmill havinggenerating functions of both photovoltaic power generation and windpower generation. This embodiment is the vertical shaft windmilldescribed in FIG. 16, to which a battery 91 for storing electric power,a solar battery cell 92 for converting solar energy into DC electricpower, a controller 93 for controlling the solar battery, and aconverter A94 and a converter B95 are added. The controller 93 controlsthe amount of power generation of the solar battery in particular.

The converters A, B are converters including an active switch. An activeswitch herein includes electric power semiconductor devices such as athyristor, a GTO, an MOS, an FET and an IGBT, having the convertingfunction from DC to AC or from AC to DC.

The changeover switch 60 having a multi-switching mechanism is connectedto the generator/motor through the converter A94 via the line L1. Thechangeover switch 60 is also connected to the battery 91 via L4, to thesolar battery cell 92 through the controller 93 via the line L2, and tothe commercial power source 100 through the converter 95 via the lineL3. Also, as described with FIG. 16, the anemometer W is connected tothe control means 90 via the signal line Li and the control means 90 isconnected to the changeover switch 60 via the output signal line Lo. Insuch an arrangement, the changeover switch 60 is controlled by thecontrol means 90.

This embodiment is the same as the foregoing embodiment described withFIG. 16 in that the coil of the generator GM is supplied with electricpower to make the generator operate as a motor, enabling rotation of thewindmill against resistance such as bearing friction even when the windvelocity is relatively low.

It is possible that electric power during operation as a motor issupplied from the commercial power source 100 while electric power issupplied to the commercial power source 100 during operation as agenerator. Also, it is possible that, through the operation of thechangeover switch 60, electric power is supplied from the battery 91during operation as a motor, while electric power is stored in thebattery 91 during power generation and supplied to an in-house powersource (not shown) or the commercial power source 100 as required. Also,it is possible that, through the operation of the changeover switch 60,electric power generated by the solar battery cell 92 is stored in thebattery 91 through the controller 93.

Lines from the commercial power source 100 to the converter B95 and fromthe converter A94 to the generator/motor GM carry a AC, and lines fromthe converter B95 through the SW 60 to the converter A94 carry an DC.Lines L2, L4 also carry a DC.

As described above, the vertical shaft windmill of an embodiment of thisinvention is characterized in that the casing (7) extends further upwardthan the lowest arm (5L), the radial bearing (BI) is fixed to the outerpart of the casing (7), and the arm (5L) is mounted for rotation to thecasing (7) through the radial bearing (BI) (see FIG. 1-FIG. 5).

In such an arrangement of the embodiment of this invention, since theinner race of the radial bearing (inner-race-fixed radial bearing BI) ismounted on part of the casing (7) as a non-rotary member and the outerrace is connected to the arm (5L), the arm (5L) is rotatable relative tothe casing (7).

Therefore, even if the casing (7) extends further upward than the lowestarm (5L), interference with the lowest arm (5L) is avoided. As a resultof the casing (7) extending further upward than the lowest arm (5L), theoverhang is shorter and the windmill (3) is stabilized.

In the embodiment of this invention, cover members (covers 9 forpreventing ingress of foreign matters) are preferably disposed radiallyoutwardly at the exterior of the radial bearing (inner-race-fixed radialbearing BI) fixed to the outer part of the casing (7) (see FIG. 1, FIG.2, FIG. 5 and FIG. 6).

Since the radial bearing (inner-race-fixed radial bearing BI) fixed tothe outer part of the casing (7) is exposed to the external environment,that is, directly exposed to the wind and rain, there might occurgeneration of rust, sticking due to insufficient lubrication andabrasion due to ingress of foreign matter, resulting in a possible lossof accuracy.

To deal with this, the cover members (covers 9 for preventing ingress offoreign matters) are disposed radially outwardly at the exterior of theradial bearing (inner-race-fixed radial bearing BI), so that theforegoing various disadvantages can be prevented.

Here, the cover members (9) are preferably made of material (forexample, a metal) of a high weather resistance and a small agingdeterioration. The cover members may also be made of plastic materialssuch as a hard rubber.

Further, a small clearance is preferably provided between the covermember (9) and arm (5L) to avoid contact resistance with the arm (5L).However, if the contact resistance is relatively small (for example, inthe case of a diaphragm or a plastic material), the cover member (9) maybe in contact with the arm (5L).

Further, the vertical windmill of an embodiment of this invention ischaracterized in that a recess (10 e) having a taper of larger radialinside and smaller radial outside (tapered off radially outwardly) isformed in the arm connection members (the couplings (10, 12) for holdingan arm therebeween from above and from below, or the flat plate-likemember 18 of FIG. 11) integrated with the respective radial bearings(the radial bearing BR disposed inside the casing 7, and theinner-race-fixed radial bearing BI disposed externally of the casing 7),and the radially inner ends of the arm (5L) are formed in the shapecomplementary to the recess (10 e) (see FIG. 1-FIG. 4, and FIG. 10).

In such an arrangement of this invention, since the recess (10 e) of thearm connection members (the couplings (10, 12) for holding an armtherebetween from above and from below, or the flat plate-like member 18of FIG. 11) and the radially inner end of the arm (5L) are formed in theshape of a taper of larger radial inside and smaller radial outside,even when centrifugal force is exerted on the arm (5L), the taperproduces reactive force against the centrifugal force, which preventsthe arm (5L) from slipping off from the arm connection members (10, 12).

Further, the vertical shaft windmill of an embodiment of this inventionis characterized in that the arm (5L) is formed hollow (preferably in athin-walled and hollow shape), and a reinforcement member (55M) madefrom light material (for example, aluminum), with a specific gravity ofno higher than 3.0, different from that of the arm (for example,reinforced resin such as FRP) is disposed at the radially inner end (onthe side of the rotary shaft) of the arm (5L), partly inserted in thearm (5L) (see FIG. 1 and FIG. 10).

Here, the arm (5L) is preferably made of FRP and has a hollow,thin-walled winglike shape.

The material for the reinforcement member (55M) is not limited toaluminum if it is small in specific gravity and high in tenacity. Ametallic material other than aluminum, such as titanium, or othermaterials with high strength can be used.

In order to dispose such a reinforcement member (55M) at the radiallyinner end of the arm (5L), the reinforcement member (55M), part of whichis inserted in the arm (5L), can be integrated with the arm (5L)satisfactorily only with adhesive in terms of strength. However, forimprovement in safety (prevention of separation of the arm 5L andreinforcement member 55M), connection with the reamer bolts (B4) ispreferable.

In this case, if the reamer bolts (B4) are disposed in a row, the arm(5L) might be broken if formed thin-walled, so that the reamer bolts(B4) are preferably disposed in a staggered relation for the preventionof arm breakage.

Further, the vertical shaft windmill (3) of an embodiment of thisinvention is characterized in that a lid-like member (20) covers theuppermost end (7C) of the casing, and a labyrinthine structure isconstituted at the portion covered with the lid-like member (20) (FIG.1, FIG. 7 and FIG. 12-FIG. 15).

Heat produced inside the casing (7) (heat produced in the generator orbearings) need to be released. In addition, since the windmill (3) isinstalled in the open air, the direct sunlight raises the temperature inthe casing (7), so that the need of releasing the heat in the casing (7)is extremely high.

However, if the casing (7) is simply formed with a heat releasing hole,rainwater will enter the casing (7) through the heat releasing hole.That is, in the prior art, it is difficult to release heat produced inthe casing (7) while preventing ingress of the rainwater.

On the other hand, in the foregoing arrangement of this invention, alabyrinthine structure is adopted at the portion of the casing at itsuppermost end (7C) covered by the lid-like member (20). Such alabyrinthine structure provides a construction in which heat in thecasing (7) can be discharged easily and ingress of the rainwater isdifficult.

Regarding the labyrinthine structure, vertically upwardly extendingpartition walls (21, 23) may be formed integrally with the casing at theuppermost end (7C), so that the labyrinthine structure is constituted byboth of the partition walls (partition walls 22, 24 of the lid-likemember 20 and partition walls 21, 23 of the casing uppermost end 7C).

In an embodiment of this invention, it is preferable that an electriccurrent (for example, commercial power 100) is supplied to the coil of agenerator (GM) housed in the casing (7) so that the generator isoperated as a motor, when the wind velocity is not so high as toovercome the static rolling resistance.

In such an arrangement, even when the wind velocity is as relatively lowas to barely overcome the rolling resistance, the windmill (3) cancontinue to rotate satisfactorily.

It is preferable that the current supply to the coil is stopped andoperation as a motor is terminated to start operation as a generator,when the windmill (3) rotates as fast as to overcome the rollingresistance.

Further, in an embodiment of this invention, a solar battery panel (110)is preferably mounted on the outside circumferential surface of thecasing (7) (preferably throughout the circumference). In this case, thesolar battery panel (110) is preferably flexible. This is because stablesolar generation can be expected irrespective of the position of the sunwith such a panel (110).

The embodiments shown in the figures are essentially illustrative andnot intended to limit the scope of this invention.

For example, while only a Darius type windmill has been described in theillustrated embodiment, this invention can be applied to a Savonius typewindmill or other vertical shaft windmills.

INDUSTRIAL APPLICABILITY

According to the vertical shaft windmill of the embodiment describedabove,

-   -   (a) since the inner race of a radial bearing is pmounted in a        casing as a non-rotary member while the outer race is connected        to an arm, the arm is rotatable relative to the casing.        Therefore, the casing is allowed to extend further upward than        the lowest arm and thus the overhang becomes shorter, and the        windmill is stabilized;    -   (b) since cover members are disposed radially outwardly at the        exterior of the radial bearing, direct exposure to wind and rain        is avoided. It prevents disadvantages of generation of rust,        sticking due to insufficient lubrication, abrasion due to        ingress of foreign matters, and the like;    -   (c) since a recess of an arm connection member and a projection        of an arm at its radially inner end are in the shape of a taper        of larger radial inside and smaller radial outside, if        centrifugal force is exerted on the arm, the taper produces        reactive force against the centrifugal force, with the recess        and the projection meshing with each other, which prevents the        arm from slipping off from the arm connection member;    -   (d) since an arm body is made of FRP and formed in a hollow,        thin-walled winglike shape, for example, and an aluminum        reinforcement member, for example, is disposed at the radially        inner end of an arm, a structure is materialized which is low in        price, short in delivery time and satisfactory in terms of        weight and strength. That is, a windmill is materialized having        a required strength, and being light in weight and high in power        generating efficiency;    -   (e) since a labyrinthine structure is adopted in which        vertically upwardly extending partition walls are formed        integrally with the casing at the uppermost end, while        vertically downwardly extending partition walls are formed        integrally with a lid-like member covering the uppermost end and        the partition walls of both members are disposed radially        alternately with each other, a structure can be provided in        which heat in the casing is discharged easily and ingress of        rainwater is difficult;    -   (f) since an electric current (for example, commercial power) is        supplied to the coil of a generator housed in the casing so that        the generator is operated as a motor when the wind velocity is        not so high as to overcome the static rolling resistance, the        windmill can continue to rotate satisfactorily even when the        wind velocity is as relatively low as to barely overcome the        rolling resistance; and    -   (g) since a solar battery panel is mounted on the outside        circumferential surface (preferably throughout the        circumference) of the casing enclosing the rotary shaft, stable        photovoltaic power generation can be expected irrespective of        the position of the sun.

1. A vertical shaft windmill comprising: a blade for receiving a wind toobtain rotational force; a plurality of arms disposed in verticalrelation for supporting the blade; a rotary shaft disposed verticallyfor receiving the rotational force of the blade through the arms; acasing for housing the rotary shaft, extending further upward than alowest arm of the plurality of arms; and a radial bearing fixed to anouter part of the casing for rotatably mounting the lowest arm to thecasing.
 2. The vertical shaft windmill as recited in claim 1, furthercomprising a cover member disposed radially outwardly at an exterior ofthe radial bearing. 3-10. (canceled)
 11. The vertical shaft windmill asrecited in claim 1, further comprising an arm connecting member placedbetween the radial bearing and the arms and formed with a recess havinga taper of larger radial inside and smaller radial outside, whereinradially inner end of the arm is formed in a shape complementary to therecess.
 12. The vertical shaft windmill as recited in claim 2, furthercomprising an arm connecting member placed between the radial bearingand the arms and formed with a recess having a taper of larger radialinside and smaller radial outside, wherein radially inner end of the armis formed in a shape complementary to the recess.
 13. The vertical shaftwindmill as recited in claim 1, wherein the arm is formed hollow andcomprises a reinforcement member made of a light material, with aspecific gravity of no larger than 3.0, different from that of the arm,the reinforcement member being disposed at the radially inner end of thearm, partly inserted in the arm.
 14. The vertical shaft windmill asrecited in claim 2, wherein the arm is formed hollow and comprises areinforcement member made of a light material, with a specific gravityof no larger than 3.0, different from that of the arm, the reinforcementmember being disposed at the radially inner end of the arm, partlyinserted in the arm.
 15. The vertical shaft windmill as recited in claim11, wherein the arm is formed hollow and comprises a reinforcementmember made of a light material, with a specific gravity of no largerthan 3.0, different from that of the arm, the reinforcement member beingdisposed at the radially inner end of the arm, partly inserted in thearm.
 16. The vertical shaft windmill as recited in claim 1, furthercomprising a lid-like member covering an uppermost end of the casing,wherein a labyrinthine structure is constituted at a portion coveredwith the lid-like member.
 17. The vertical shaft windmill as recited inclaim 2, further comprising a lid-like member covering an uppermost endof the casing, wherein a labyrinthine structure is constituted at aportion covered with the lid-like member.
 18. The vertical shaftwindmill as recited in claim 11, further comprising a lid-like membercovering an uppermost end of the casing, wherein a labyrinthinestructure is constituted at a portion covered with the lid-like member.19. The vertical shaft windmill as recited in claim 13, furthercomprising a lid-like member covering an uppermost end of the casing,wherein a labyrinthine structure is constituted at a portion coveredwith the lid-like member.
 20. The vertical shaft windmill as recited inclaim 1, further comprising a generator driven by the rotational forceof the rotary shaft, wherein the rotary shaft is constituted integrallywith a rotary shaft of the generator.
 21. The vertical shaft windmill asrecited in claim 2, further comprising a generator driven by therotational force of the rotary shaft, wherein the rotary shaft isconstituted integrally with a rotary shaft of the generator.
 22. Thevertical shaft windmill as recited in claim 11, further comprising agenerator driven by the rotational force of the rotary shaft, whereinthe rotary shaft is constituted integrally with a rotary shaft of thegenerator.
 23. The vertical shaft windmill as recited in claim 13,further comprising a generator driven by the rotational force of therotary shaft, wherein the rotary shaft is constituted integrally with arotary shaft of the generator.
 24. The vertical shaft windmill asrecited in claim 16, further comprising a generator driven by therotational force of the rotary shaft, wherein the rotary shaft isconstituted integrally with a rotary shaft of the generator.
 25. Thevertical shaft windmill as recited in claim 20, further comprising asolar battery panel mounted on an outside circumference of the casing.26. The vertical shaft windmill as recited in claim 20, wherein thegenerator is adapted to operate also as a motor.
 27. The vertical shaftwindmill as recited in claim 25, wherein the generator is adapted tooperate also as a motor.
 28. The vertical shaft windmill as recited inclaim 26, wherein the generator is adapted to: supply electric power toa commercial power source when operating as a generator; and be suppliedwith electric power from the commercial power source when operating as amotor.
 29. The vertical shaft windmill as recited in claim 26, furthercomprising a battery for storing electric power, wherein the generatoris adapted to: be supplied with electric power from the battery whenoperating as a motor; and store electric power in the battery so as tosupply electric power from the battery to a commercial power source oras in-house electric power, as required, when operating as a generator.